Golovkin ties record in devastating second-round KO against Martirosyan

Undefeated middleweight champion Gennady Golovkin was in a merciless mood after his blockbuster rematch with Saul 'Canelo' Alvarez was cancelled as he knocked out Vanes Martirosyan in the second round.

Martirosyan (36-4-1) stepped in at the last minute for powerful Mexican Alvarez, who withdrew from the scheduled bout having received a six-month suspension for testing positive for banned substance clenbuterol.

And Golovkin (38-0-1, 34 KOs) - who put his WBA, WBC and IBF titles on the line - did not waste any time against Martirosyan as he produced a devastating knockout in the second round at StubHub Center in California Saturday.

Only announced as Golovkin's new opponent April 18, Martirosyan rarely troubled the 35-year-old Kazakh, though he managed to deliver a right-left combination in the first round.

However, that was as good as it got for the 36-year-old - Golovkin hitting Martirosyan with a flurry of punches in the second that floored his Armenian-American opponent face first and left him down for the count.

Referee Jack Reiss ended the fight at one minute, 53 seconds as Golovkin retained his title for a record 20th successive time - tying the division mark set by Bernard Hopkins in 2005.